1. Technical Field
The present invention relates to a method of stirring liquid in a droplet discharge head and to a droplet discharge apparatus.
2. Related Art
In a droplet discharge head used in a droplet discharge printer, a blotter, or another recording apparatus, there is a possibility that water or another ink solvent will evaporate in the nozzle opening, and the ink viscosity will increase to be greater than necessary. An increase in the ink viscosity that is greater than necessary leads to defects such as decreasing of the size (weight) of the ink drops (droplets).
Particularly in cases in which a liquid that could possibly precipitate is used, such as a nonaqueous solvent-based ink that uses a pigment for the coloring material, a dispersion-based ink, or a UV curing ink, reducing the size of the nozzle opening or occasionally blocking off the nozzle opening are considered as options.
In view of this, Japanese Laid-open Patent Application Nos. 2000-085125 and 2001-270134 disclose techniques in which microvibration that is insufficient for ink discharge is induced in the meniscus in the nozzle opening, whereby the ink in the nozzle opening is stirred and the ink viscosity is maintained.
However, the conventional techniques described above have the following problems.
Since the aforementioned ink stirring is performed at a pressure in a range at which the ink is not discharged, it has been difficult to classify the stirring as being sufficient.
Particularly in cases in which one of the aforementioned precipitation-capable liquids is used, precipitation could possibly occur not only in the nozzle opening but also in the ink channel for feeding the ink to the nozzle, but it is extremely difficult with the microvibration to stir the ink in the ink channel, which is in a position separated from the nozzle opening.